On 30 Mar 00, at 13:37, Nathan Russell wrote:
> What are the thresholds after which Prime95 does an additional bit of
> factoring?
>From the file common.h in the (publically available) source for v19:
/* Factoring limits based on complex formulas given the speed of the
*/
/* factoring code vs. the speed of the Lucas-Lehmer code */
#define FAC72 71000000L
#define FAC71 57020000L
#define FAC70 44150000L
#define FAC69 35100000L
#define FAC68 28130000L
#define FAC67 21590000L
#define FAC66 17850000L
#define FAC65 13380000L
#define FAC64 8250000L
#define FAC63 6515000L
#define FAC62 5160000L
#define FAC61 3960000L
#define FAC60 2950000L
#define FAC59 2360000L
#define FAC58 1930000L
#define FAC57 1480000L
#define FAC56 1000000L
The reason there is a bigger band than you'd expect for 64 bits (from
8.25 million to 13.38 million) is that there is a sharp efficiency
drop when you go to 65 bits for reasons intimately bound with the
word length of the CPU.
Regards
Brian Beesley
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